How can I properly form text from particles?
To change the shape of an object using particles, use the physics type Keyed.


Create an emitting object, cube or whatever.
Create a text object, convert it to mesh Alt-C and add another particle system.
Create a controller (e.g. simple plane with a 3rd particle system) and add the previously created particle systems as keys.


Here with a tiny version of the cube used as Dupli Object.
Use a massive number of particles not just a few hundred.



Tutorials


Blender Keyed Particle System Tutorial
Blender 2.68 Tutorial - Various Text Reveals
Blender 2.6 Tutorial - Keyed Particles versus Curve Guides